1. Field of the Invention
The present invention relates to the method and apparatus for producing an image defined by fluid bubbles in a medium fluid. In particular, alphanumeric digits and/or graphic images in a fluid medium are formed by injecting into the fluid medium a multitude of fluid bubbles having a density different than that of the medium fluid.
2. Description of the Related Art
It is important that signs and displays which advertise a product be distinctive and unique. For instance, a corporation's image can be enhanced through the display of its corporate logo, using custom signage. Similarly, if an advertisement for a particular product is made visually unique, its sales may be increased. One way of making unique displays is the use of a liquid or gas to create an image. The image may be produced as a random shape or as a message display.
U.S. Pat. No. 4,034,493 to Ball shows how liquids of different specific gravities and selected viscosities are located in a chamber defined by two closely spaced panes or plates of a transparent material for producing a visual effect.
U.S. Pat. No. 5,349,771 to Burnett teaches a rising bubble display device including a reservoir with a lamp positioned beneath the reservoir. An air pump is mounted near the lamp, which forces bubbles up through a colored or translucent liquid, complemented by a colored light from the lamp.
U.S. Pat. No. 5,617,657 to Kahn demonstrates a multi-color liquid display system comprising a transparent conduit and system for sequentially circulating liquids of different color and different specific gravity through the conduit to present a dynamic display such as "raining" of one liquid into another.
U.S. Pat. No. 3,973,340 to Khawand shows a visual display with one or more conduits are provided in which immiscible fluids are placed for creating a predetermined visual pattern.
U.S. Pat. No. 3,717,945 teaches how liquid jets are separated into streams of individual drops to provide a three-dimensional image.
U.S. Pat. No. 5,363,577 shows a liquid display system that has a plurality of adjacent parallel tubes filled with a fluid and connected to a source of air that introduces bubbles into the I1 tubes, so that the combination of bubbles form a word, or another graphic display.
U.S. Pat. No. 5,737,860 demonstrates a device for forming a changeable sign of bubbles rising within a body of liquid or from drops of liquid moving through the air. Solenoid valves release bubbles, which are interrupted so as to produce bubbles in an array that displays a message.
In contrast with the above prior art, the present invention utilizes bubbles made from non-gaseous fluids, and allows the fluid bubbles to take on a natural shape which is not confined by any structures as it travels through the medium fluid. The rate at which the fluid bubbles rise or fall through a medium fluid is directly dependent on the viscosity (.eta.) of the medium fluid. A more viscous medium fluid will result in the fluid bubbles rising at a slower rate. This control over the speed of travel is desirable to allow for complex images to be created, or allow for size variation in device. For example, if the device is only 13-cm tall, then it is desirable for the bubbles to rise to the surface slower than in a device that is 130-cm tall.
Since the medium and bubbles fluids become more viscous as the ambient temperature of the surroundings is decreased, the resulting viscosity will also depend upon the temperature extremes that the device will be required to function within.
The viscosity of the medium fluid also influences the rate of formation of bubbles which are being created. If a large quantity of bubbles are being created to form an image, then the medium fluid may become turbulent and make the image indistinguishable before it arrives to the surface of the medium fluid. The selection of a more viscous medium fluid produces less turbulence.
Also pertinent to design of BIT devices is the viscosity of the bubble fluid. The more viscous the fluid medium, the larger the bubble can be and still remain spherical. If the bubble is too large for a given bubble fluid, then the bubble becomes unsteady and may deform, or split into multiple bubbles. This decreases the clarity and lowers the quality of the bubble image.
Because of the dependency of both mediums on their respective viscosities, the relative viscosity between the two fluids is an important consideration when selecting the fluids. Similarly, properties such as density and specific gravity, and heat capacity play a part in the selection of fluids.
The respective fluids may also have a low freezing point to resist freezing, which may damage the internal components of the device, or crack the viewing windows. Also, the color of the fluid should not deteriorate from exposure to either sunlight or artificial light. This allows the device to provide vivid, high color images for the life of the product.
Thus, to create an apparatus which displays an aesthetically pleasing message or image, the requisite properties of the respective fluids is the most important consideration. The fluids are thereafter controlled by coupling with timing circuitry to operate an array of bubble generators, allowing for production of a colorful, long-lasting, and accurate representation of a timed message display. An example of such a product is a clock which incrementally displays the time, alphanumerically, by the release of liquid bubbles in a fluid medium.
The control and timing circuitry determines the time interval wherein the horizontal row of bubbles is created. Several horizontal rows of bubbles are created until the full vertical length of an alphanumeric digit or graphic is achieved. In one embodiment, the bubble release means includes a mechanical plunger provided for each row of bubbles. Each plunger position and timing is controlled by an electromagnet and associated control and timing electronics. Possible variations and modifications to the bubble generation include utilizing a fluid pump and over-pressure valve. The preferred method utilizes a bubble generation means that has no moving parts, using piezo devices and flow-control valves.